1. Field of the Invention
The present invention relates to a testing apparatus for detecting and evaluating inclination of an image plane as caused by decentering of an optical system, and to an adjusting apparatus for correcting such inclination.
2. Description of the Prior Art
It is well known that decentering of an optical system with respect to its optical axis causes decentering-related aberrations such as axial coma, in which even axial light rays exhibit coma that extends along the optical axis, and one-sided blurring, in which off-axial light rays striking different parts of the periphery of a screen focus on different positions along the optical axis. As an apparatus for testing and adjusting imaging performance of an optical system in such aspects, Japanese Laid-open Patent Application No. H6-265766 discloses an optical axis adjusting apparatus for use in a lens system, though it only corrects axial coma mentioned above.
However, in recent years, as higher and higher magnifications are realized in zoom optical systems for single-lens reflex cameras, it is becoming more and more difficult to obtain desired optical performance in end products simply by producing components to such precision as is conventionally required, and it is becoming necessary to correct also one-sided blurring mentioned above. Conventionally, whereas a method for correcting axial coma has been well established, no convenient method has been known to date for quickly checking the optical performance at the periphery of a screen to detect one-sided blurring in particular and make appropriate adjustments.